It's probably 50% of students going on to post grad residencies. I hate it when schools try to use that as the number when asked about specialty rate (Heard an administrator here doing the same this week).
The only information that could possibly be worthwhile is the # of students who got into endo, pedo, ortho and OMFS (which I declare is now called the EPOO statistic), and even then it only really means something if you know the number of students that applied. There's no school in the nation that's going to make it significantly harder for you to specialize, and you're going to have to work your butt off no matter where you go.